Impact Fatigue Crack Growth Behavior at Low Temperatures
TLDR
In this paper, the influence of ductile-brittle transition temperature and test temperature on the impact fatigue crack growth rate was investigated by means of fracture mechanics and fractography in quenched and tempered Cr-Mo alloy steel in which the prior austenite grain size was varried from 8.3 to 25.4μm.Abstract:
The impact fatigue tests were carried out using a rotating disk type impact fatigue testing machine. The influence of ductile-brittle transition temperature and test temperature on the impact fatigue crack growth rate was investigated by means of fracture mechanics and fractography in quenched and tempered Cr-Mo alloy steel in which the prior austenite grain size was varried from 8.3 to 25.4μm, and the results of impact fatigue tests were compared with those of non-impact fatigue tests. The results obtained were as follows.(1) The impact fatigue and non-impact fatigue crack growth rates associated with striation formation at stage IIb were insensitive to the change in ductile-brittle transition temperature and test temperature.(2) In impact fatigue, it was found that the impact loading gave rise to transition of dominant fracture appearance from striation formation at stage IIb to intergranular cracking and cleavage at stage IIc as the Charpy impact value was decreased.(3) In impact fatigue, the transition of dominant fracture appearance from exclusively striation formation to intergranular cracking and cleavage was found to result in the acceleration of crack growth rate. The relation between the m value in Paris's equation and the ratio of test temperature, T, to ductile-brittle transition temperature, TM, was expressed as follows.m=1.12(T/TM)-1.99.read more
Citations
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Journal ArticleDOI
The impact fatigue properties of iron and steel
TL;DR: In this article, it was shown that an iron or steel specimen undergoing impact fatigue has an unusually high ultimate tensile strength and ductile-brittle transition temperature, which can explain some of the main features of impact fatigue behavior such as the high endurance relative to conventional fatigue for a given stress level, and the tendency to exhibit cleavage rather than a ductile fracture mode.
Book ChapterDOI
Crack growth behavior under repeated impact load conditions
TL;DR: In this paper, the authors evaluated the impact fatigue properties of metallic materials under simple impact load patterns and found that fatigue strength in impact fatigue is lower than that in non-impact fatigue except for the case of torsional impact fatigue.
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